How to execute a method from the console
But it did not really execute.


Based on my understanding of Blender, an operator cannot be directly executed.
It should be called from Blender internal.

Try

bpy.ops.object.hello_world()

Where hello_world is the name you registered to Blender system using bl_idname.

More details if you are interested:

When a request of operator invoking is arrived, Blender internal(the source code looks like a factory) will create an Operator instance dynamically, and call your execute function there. You should not call it yourself IMO.


  but I wish to call a variable from an addon and use it in a different addon


In your case I think you may want to have some utility functions shared with other addons.
I suggest to write these utility functions as normal Python function and pass the context to it from your addons.